Note: Descriptions are shown in the official language in which they were submitted.
CA 02984689 2017-11-01
Y \ KDI01\5279 CA CIPONFtplernt 0esc171101.6pd
ZIPLINE TROLLEY RELEASE AND SPEED LIMITER
Cross Reference to Related Application
[0001] This application claims the benefit of US Provisional Patent
Application No.
62/170,387, filed 3 June 2015.
Technical Field
[0002] The present invention relates to the field of ziplines. More
particularly, the
invention relates to holders and launching devices, and speed-limiting
devices, for zipline
trolleys.
Background Art
[0003] In simple terms, a zipline involves a suspended inclined cable and a
sheave
assembly free to move along the length of the cable. In most ziplines, the
user is
supported by a seat or harness that is secured to the sheave assembly.
Propelled by
gravity, the user rides from the upper end of the cable towards the lower end
of the cable.
[0004] In its simplest form, the sheave assembly may be a pulley with a
single
sheave. However, it is common for the sheave assembly to be a trolley with two
or more
sheaves, as multiple sheaves distribute the load over more than one spot on
the cable
(thus reducing cable bending stresses that may lead to metal fatigue and cable
breakage).
[0005] Zipline cables can be very high, generally starting at a height of
over 9 m (30
ft) and in some cases much higher, and traveling well over 460 m (1,510 ft). A
pivoting
link, such as a carabiner, is used to secure the load to the trolley. Load
carriers include
enclosed cabins and gondolas, but more commonly the load carrier is a single-
person
harness or seat. It is of course very important to ensure that the rider is
properly secured
in the harness or seat before they are launch down the zipline cable.
[0006] The maximum velocity attained by a zipline rider and the rider's end
velocity
(i.e., the rider's velocity at the lower end of the cable), depend on a
variety of factors,
including the average incline (i.e., the rise over the run; that is, the
difference in height
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between the cable upper end and the cable lower end, divided by the horizontal
distance
between the cable upper end and the cable lower end); and the cable tension.
As the
cable ends are at different heights, an installed zipline cable assumes a
skewed catenary
curve under the force of gravity, such that the greatest downward incline (and
thus
greatest acceleration) is in the vicinity of the upper end of the cable, and
the lower end of
the cable has at least some upward incline (and thus at least some
decelerating effect).
Thus, in some circumstances, to a certain extent, zipline velocity may be
"tuned" by
adjusting the cable tension, as, all other things being equal, higher tension
produces lower
initial acceleration and lower terminal deceleration.
[0007] However, "tuning" zipline velocity by adjusting cable tension is
usually not
completely effective in terms of producing a consistent desirable rider
maximum velocity
and end velocity. In many installations, cable tension is constrained by the
terrain, for
example a desired sag in terms of end velocity may bring the cable within an
unsafe
proximity to the ground, trees etc.. Further, the rider's weight affects
velocity. It is
understood that heavier rider's achieve higher velocities than lighter riders
because force
(mass times acceleration) increases more with rider weight than rider wind
resistance (and
any other weight-dependent decelerators, e.g., sheave friction etc.). As well,
the rider's
weight distorts the cable curve, such that, put simply, at the start of a
zipline ride, the cable
slope (and thus acceleration) is greater for a heavier person than for a
lighter person. As
well, the wind direction (e.g., tail wind or head wind) and strength affect
velocity.
[0008] Various means of slowing and stopping a zipline rider have been
used,
including: thick purpose-built leather gloves; a mat or netting at the lower
end of the
incline; a passive arrester system composed of springs, pulleys,
counterweights, bungee
cord, tire or other devices, which slows and then stops the trolley's motion;
a "capture
block" which is a block on the cable that is actuated by a rope held by an
operator who
can manually apply friction to slow a zipline rider; and rider-operated hand
brakes.
[0009] US 8,336,463, Smith, ZIPLINE TROLLEY SYSTEM, 25 December 2012,
discloses a trolley configured to engage with: a launcher fixed to the upper
end of the
cable, that in use is reversably pivoted roughly 90 degrees about the cable to
secure and
then launch the trolley; and a catch block fixed to the lower end of the
cable, for catching
and releasably securing the trolley.
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Disclosure of Invention
[0010] In one aspect, the present invention provides a zipline system
including a
trolley holder/launcher and a speed-limited trolley intended to increase
operational safety.
[0011] The trolley holder/launcher has a manipulable actuator requiring two
distinct
sequential movements by the operator in order to launch a trolley. In a
preferred
embodiment, the first movement is a linear movement of a hand grip to change
the
actuator from a locked to an unlocked position and the second movement is a
pivotal
movement of the grip to change the actuator from an engagement position to a
disengaged position. The actuator includes a spring that resiliently biases
the hand grip
to maintain the actuator in the locked position and preferably includes a
spring that
resiliently biases the hand grip to maintain the actuator in the engagement
position.
[0012] The speed-limited trolley includes eddy current speed limiting. Eddy
current
speed limiting occurs when a conductor is moved past (i.e., through) a
magnetic field,
producing a current in the conductor that in turn produces a magnetic field
that resists the
motion of the conductor. This resistive force is proportional to the speed at
which the
conductor moves past the magnet. Eddy current braking results in some by-
product heat
in the conductor because of the current flowing therein.
[0013] The speed-limited trolley embodiments of the present invention
provide
eddy current speed limiting through the interaction of rare-earth magnets and
enhanced-
conductor sheaves. Enhanced-conductor sheave embodiments have sheave sides
having
conductive material of a greater diameter and/or greater thickness, as
compared to
conventional sheaves. The conductive material (i.e., the conductor part of the
eddy
current speed limiter) is non-ferromagnetic. Suitable non-ferromagnetic
conductor
materials include aluminum containing metals and copper containing metals
(e.g., copper
and brass). Gold and silver containing metals would presumably also be
suitable from a
performance perspective but likely not from a cost perspective.
[0014] In preferred embodiments, the rare-earth magnets are mounted to the
trolley
side plates.
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[0015] The positioning of the magnets relative to the sheave sides of the
enhanced-
conductor sheaves affects the speed-limiting effect. The inventor understands
that in
terms of magnet position and speed-limiting effect, the two most significant
factors are:
the radial distance between the axis of rotation of the enhanced-conductor
sheave and a
magnet (which can also be thought of in terms of the radial distance between
the magnet
and the circumferential periphery of an enhanced-conductor disc portion of the
sheave
sides), and the proximity of the magnet to the sheave side (i.e., the gap
between the
magnet and the surface of the enhanced-conductor disc portion of the sheave
side).
Increasing the radial distance between the axis of rotation of the enhanced-
conductor
sheave and a magnet, increases the speed-limiting effect of the magnet (so
long as the
magnet remains within the circumferential periphery of the enhanced-conductor
disc
portion of the sheave sides). Decreasing the gap between the magnet and the
surface
of the enhanced-conductor disc portion of the sheave side increases the speed-
limiting
effect of the magnet.
[0016] The number of magnets also affects the speed-limiting effect; in
that, all
other things being equal (e.g., magnet positioning and magnet strength),
increasing the
number of magnets increases the speed-limiting effect. However, adding magnets
does
not increase the speed-limiting effect in a linear manner. Although, two or
more installed
similar magnets will in use each induce a similar speed-limiting effect, to
understand why
speed limiting does not increase in a linear manner, it is useful to imagine a
situation in
which magnets are being added. The eddy current speed-limiting effect is
proportional to
the speed at which the conductor moves past the magnet(s). Thus, once one or
more
magnets are installed, they will have reduced the speed at which the conductor
moves
past the magnets. Thus, the maximum speed-limiting effect of each additional
magnet will
be reduced due to the reduction in maximum speed resulting from the magnets
already
in place. As a result, merely increasing the number of magnets results in
diminishing
returns in terms of speed-limiting effect.
[0017] In embodiments in which two or more magnets are mounted in proximity
to
each sheave side, it has been found that the spacing of the magnets relative
to each other
affects the speed-limiting effect. Spacing adjacent magnets apart by a
distance no smaller
than the magnets' diameter is desirable. In a preferred embodiments, adjacent
magnets
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are spaced apart a distance equal to the magnets' diameter.
[0018] In embodiments in which two or more magnets are mounted in proximity
to
each sheave side and the magnets are spaced apart, one from the other, a
distance equal
to the magnets' diameter, the inventor has not found any appreciable
difference in the
speed limiting effect between magnets oriented to have the same polarity and
magnets
oriented to have opposite polarities. It is speculated that orienting adjacent
to magnets
to have opposite polarities could affect the speed limiting effect if the
spacing of the
magnets were different.
[0019] Magnet strength also affects the speed-limiting effect. However, it
is
understood that within the range of magnet strengths in the commercially
readily available
rare-earth magnets that are suitable in terms of their size for use in a
zipline trolley, as a
practical design consideration, magnet strength is less significant than
magnet positioning.
[0020] In one aspect, the present invention provides devices for use with a
zipline
cable, the devices including: a speed-limiting zipline trolley comprising: two
trolley sides
in a spaced apart relationship; and one or more sheaves, each interposed
between, and
rotatably mounted to, the trolley sides and each sheave defining a sheave axis
of rotation;
wherein the trolley sides comprise a plate eddy current speed-limiting
component and at
least one of the sheaves comprises a sheave eddy current speed-limiting
component; and
whereby, in use, the plate eddy current speed-limiting component and the
sheave eddy
current speed-limiting component interact to produce eddy current speed
limiting.
[0021] The plate eddy current speed-limiting component may be a magnetic
field
source and the sheave eddy current speed-limiting component may be a
conductor.
[0022] The at least one of the sheaves comprising the sheave eddy current
speed-limiting component, may have a sheave side and the conductor may be a
disc of
conductive material at the sheave side; and the magnetic field source may
include one or
more magnets mounted in one of the trolley sides proximate to the disc of
conductive
material.
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[0023] The at least one of the sheaves comprising the sheave eddy current
speed-limiting component, may have two sheave sides and the conductor may be
two
discs of conductive material, wherein:one of the discs of conductive material
may be at
one of the sheave sides; and the other of the discs of conductive material may
be at the
other of the sheave sides; and the magnetic field source may include two
magnet sets for
each sheave, each magnet set including one or more magnets, wherein one of the
magnet
sets may be mounted in one of the trolley sides at a location proximate to one
of the discs
of conductive material; and the other of the magnet sets may be mounted in the
other of
the trolley sides at a location proximate to the other of the discs of
conductive material.
[0024] Each disc of conductive material may be: an aluminum-containing disc
integral to the sheave; a copper-containing disc affixed to the sheave; or an
aluminum-containing disc affixed to the sheave.
[0025] Each disc of conductive material may be a circular disc having a
planar
surface and defining a disc circle substantially concentric with the sheave
axis of rotation
and defining a disc circle circumference; and for each magnet of each magnet
set, the
location proximate to the one of the discs of conductive material may be: at a
distance
from the planar surface no greater than about 1/16"; and within the disc
circle
circumference and at a distance from the disc circle circumference no greater
than about
1/8". For each magnet of each magnet set, the location proximate to the one of
the discs
of conductive material may be: at a distance from the planar surface no
greater than about
1/32"; and at a distance from the disc circle circumference no greater than
about 1/16".
[0026] Each magnet may be a cylindrical neodymium rare-earth magnet. Each
magnet may be a 3/4" by 1/4" magnet or a 3/4" by 5/16" magnet. Each magnet set
may
include three magnets and each magnet may be a cylindrical neodymium rare-
earth
magnet.
[0027] The at least one of the sheaves comprising the sheave eddy current
speed-limiting component, may be two sheaves; each disc of conductive material
may be
a circular disc having a planar surface and defining a disc circle
substantially concentric
with the sheave axis of rotation and defining a disc circle circumference; and
for each
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magnet of each magnet set, the location proximate to the one of the discs of
conductive
material may be: at a distance from the planar surface no greater than about
1/16"; and
within the disc circle circumference and at a distance from the disc circle
circumference
no greater than about 1/8".
[0028] Each magnet set may include three magnets; each magnet may be a
cylindrical neodymium rare-earth 3/4" by 5/16" magnet; each disc circle may
have a
diameter of about 4"; and for each magnet of each magnet set, the location
proximate to
the one of the discs of conductive material may be: at a distance from the
planar surface
no greater than about 1/32"; and within the disc circle circumference and at a
distance
from the disc circle circumference no greater than about 1/16".
[0029] Each magnet set may include one magnet; each magnet may be a
cylindrical
neodymium rare-earth 3/4" by 1/4" magnet; each disc circle may have a diameter
of about
3"; and for each magnet of each magnet set, the location proximate to the one
of the discs
of conductive material may be: at a distance from the planar surface no
greater than about
1/32"; and within the disc circle circumference and at a distance from the
disc circle
circumference no greater than about 1/8".
[0030] The devices may include a trolley holder device, including: fixing
means for
fixing the trolley holder device relative to a zipline cable; an actuating arm
having: a bar,
pivotally mounted to the fixing means for pivotal movement between an
engagement
position and a disengaged position, and the bar having a latch for engaging
the trolley so
as to impede movement of the trolley away from the trolley holder device when
the bar is
in the engagement position; and a grip, slidably engaged with the bar so as to
be linearly
manipulable between: a locked engagement position in which the grip abuts the
fixing
means so as to impede pivotal movement of the bar from the engagement position
and
an unlocked position in which pivotal movement of the bar from the engagement
position
is not impeded by abutment between the grip and the fixing means; and a lock
biasing
means for resiliently biasing the grip in the locked engagement position;
whereby, when
the latch is engaged with the trolley and the grip is in the locked engagement
position,
disengaging the latch from the trolley requires sequential linear movement of
the grip from
the locked engagement position to the unlocked position and pivotal movement
of the bar
from the engagement position to the disengaged position.
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[0031] The trolley holder may include a pivot biasing means for resiliently
biasing
the bar in the engagement position. The lock biasing means may be a first
spring
interposed between the bar and the grip; and the pivot biasing means may be a
second
spring interposed between the bar and the fixing means.
[0032] The trolley may include a tooth receptacle having an inner catch;
and the
latch may include a tooth that fits within the tooth receptacle when the latch
is engaged
with the trolley, whereby the impeding of movement of the trolley away from
the trolley
holder device is provided by abutment between the tooth and the tooth
receptacle inner
catch.
[0033] In another aspect, the present invention provides a trolley holder
for use in
releasably holding a zipline trolley in a zipline installation including a
zipline cable, the
trolley holder including: fixing means for fixing the trolley holder relative
to the zipline
cable; an actuating arm having: a bar, pivotally mounted to the fixing means
for pivotal
movement between an engagement position and a disengaged position, and the bar
having a latch for engaging a zipline trolley so as to impede movement of the
trolley away
from the trolley holder when the bar is in the engagement position; and a
grip, slidably
engaged with the bar so as to be linearly manipulable between: a locked
engagement
position in which the grip abuts the fixing means so as to impede pivotal
movement of the
bar from the engagement position and an unlocked position in which pivotal
movement
of the bar from the engagement position is not impeded by abutment between the
grip and
the fixing means; and a lock biasing means for resiliently biasing the grip in
the locked
engagement position; whereby, when the latch is engaged with the trolley and
the grip is
in the locked engagement position, disengaging the latch from the trolley
requires
sequential linear movement of the grip from the locked engagement position to
the
unlocked position and pivotal movement of the bar from the engagement position
to the
disengaged position.
[0034] The trolley holder may include a pivot biasing means for resiliently
biasing
the bar in the engagement position. The trolley may include a tooth receptacle
having an
inner catch; and the latch may include a tooth that fits within the tooth
receptacle when the
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latch is engaged with the trolley, whereby the impeding of movement of the
trolley away
from the trolley holder device is provided by abutment between the tooth and
the tooth
receptacle inner catch.
Brief Description of Drawings
[0035] Fig. 1 is a side elevation partially transparent view of a zipline
cable, a
conventional zipline trolley (with two spreader-bar lanyards), and a trolley
holder
embodiment of the present invention, shown with the trolley holder in the
locked position
and engaged with the trolley.
[0036] Fig. 2 is a side elevation view of the cable, trolley and trolley
holder
embodiment of Figure 1, shown with the trolley holder in the release position
and
disengaged from the trolley.
[0037] Fig. 3 is side elevation exploded view of the actuating arm of the
trolley
holder embodiment shown in Fig. 1 and Fig. 2.
[0038] Fig. 4 is a side elevation view of a conventional trolley sheave.
[0039] Fig. 5 is sectional view of the conventional trolley sheave shown in
Fig. 4.
[0040] Fig. 6 is a sectional view of a trolley sheave with a small brake
disc attached
on each side.
[0041] Fig. 7 is a side elevation view of one of the small brake discs of
Fig. 6.
[0042] Fig. 8 is a side elevation partially transparent view of a zipline
cable and a
four-magnet small-brake-disc speed-limiter trolley (with two spreader-bar
lanyards)
embodiment of the present invention.
[0043] Fig. 9 is an end elevation partially transparent view of a trolley
showing the
spreader bar.
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[0044] Fig. 10 is a side elevation transparent view of a large-brake-disc
sheave
embodiment of the present invention.
[0045] Fig. Ills a sectional view the large-brake-disc sheave embodiment of
Fig.
10.
[0046] Fig. 12 is a side elevation view of an integral-brake-disc sheave
embodiment
of the present invention.
[0047] Fig. 13 is a sectional view of the integral-brake-disc sheave
embodiment
shown in Fig. 12.
[0048] Fig. 14 is a side elevation view of a zipline cable and a twelve-
magnet
speed-limiter trolley (with two spreader-bar lines) embodiment of the present
invention.
[0049] Fig. 15 is a side elevation view of one of the three magnet
retainers of the
twelve-magnet speed-limiter trolley embodiment shown in Fig. 14.
[0050] Fig. 16 is an end elevation view of one of the cable-guide end
spacers of the
trolleys shown in the drawings.
[0051] Fig. 17 is a side elevation view of the cable-guide end spacer shown
in Fig.
16.
[0052] Fig. 18 is a top plan view of the middle spacer of the trolleys
shown in the
drawings.
[0053] Fig. 19 is a side elevation view of the middle spacer shown in Fig.
18.
Detailed Description with Reference to the Drawings
[0054] Fig. 1 and Fig. 2 show a zipline cable 50, a conventional trolley
52, and a
trolley holder 54 embodiment of the present invention.
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[0055] The cable used for many ziplines is typically 1/2" - 7/8" galvanized
or
stainless steel cable. In this description and the drawings, the zipline cable
50 is 7/8"
galvanized steel cable and the dimensions for other components are understood
to be
suitable for use with such cable. If another cable size were used, the
dimensions of other
components would of course be modified accordingly.
[0056] The conventional trolley 52 has: two conventional trolley sheaves
60, two
sheave axle pins 62, (each sheave axle pin 62 passing through two axle support
holes 63),
two conventional trolley side plates 64, two cable-guide end spacers 66 (shown
in Fig. 16
and Fig. 17), and one middle spacer 68 (shown in Fig. 18 and Fig. 19).
[0057] The conventional trolley side plates 64 shown in the drawings each
have a
spreader-bar lanyard connector 70, which in use is attached a spreader-bar
lanyard 72
extending to a spreader-bar end 74. Spreader bar 76 is shown in Fig. 9. Some
trolleys
have four spreader-bar lanyard connectors 70, with two spreader-bar lanyards
72
extending to each spreader-bar end 74
[0058] As shown in Fig. 4 and Fig. 5, the conventional trolley sheave 60
includes
a regular hub 80, typically made from metal, typically aluminum; a cable
groove 82, being
a grooved annular component affixed to the external circumference of the
regular hub 80,
for rotating along the zipline cable 50 during use. The cable groove 82 is
made from a
material selected to provide acceptable usable life while avoiding wear to the
zipline cable
50, for example, urethane rubber.
[0059] All of the sheaves described herein, shown in the drawings and
tested by the
inventor, have an external diameter of 4" and a cable groove minimum diameter
(i.e., the
diameter measured between the deepest portion of the cable groove 82 and an
opposite
deepest portion of the cable groove 82). These sheaves are configured for 7/8"
zipline
cable, and will accommodate smaller cables. The inventor has found that the
sheaves
provide acceptable performance with 3/8", 1/2", 5/8" and 3/4" cable.
[0060] The interior of the regular hub 80 includes: a bearing seat 84, in
which a
sheave axle pin bearing 86 is fitted; and a retainer ring seat 88 in which a
retainer ring (not
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shown) is positioned to secure the sheave axle pin bearing 86 in the bearing
seat 84.
[0061] The trolley holder 54 includes a clamp assembly 90 and an actuating
arm
92 pivotally mounted to the clamp assembly 90.
[0062] The clamp assembly 90 shown in the drawings comprises an inner block
94
and a clamp outer housing 96. The inner block 94 is slightly thinner than the
diameter of
the zipline cable 50, and includes a pivot spring recess 98 for containing the
pivot spring
100. The clamp outer housing 96 is made from a piece of metal plate
(preferably 1/8"
6061 aluminum), shaped (e.g., around a mandrel) to have a central 180 degree
curve of
a diameter no greater than the zipline cable 50. The inner block 94 and clamp
outer
housing 96 have three aligned clamp holes 102 for receiving clamp bolts 104,
for installing
and maintaining the clamp assembly 90 at a desired position on the zipline
cable 50.
[0063] The inner block 94 and clamp outer housing 96 are preferably made
from
aluminum. To reduce the galvanic action that would otherwise result from the
electrical
contact between the dissimilar metals (i.e., steel and aluminum), an
electrical insulating
layer (e.g. conventional vinyl electrical tape) should be interposed between
the cable 50,
and the inner block 94 and clamp outer housing 96.
[0064] The inner block 94 and clamp outer housing 96 may be used with
smaller
sized cables by interposing a shim-spacer (not shown in the drawings) between
the cable,
and the inner block 94 and clamp outer housing 96. Preferably, the shim-spacer
is curved
and sized to substantially conform to the outer periphery of the cable. It is
understood that
a section of a pipe with a longitudinal slit such that the pipe may be sprung
apart when
being fitted on a cable, may be a suitable shim-spacer. Alternatively, a
suitable pipe cut
longitudinally to make two (or more) curved sections that may be slid between
a cable,
and the inner block 94 and clamp outer housing 96, may be a suitable shim-
spacer. Non-
metal materials, including materials with electrical insulation properties,
may be suitable
for the shim-spacer. If the shim-spacer is made from metal, to reduce galvanic
action the
metal should be the same as the metal of the inner block 94 and clamp outer
housing 96.
[0065] The clamp outer housing 96 includes two aligned housing pivot holes
106
12
=
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for receiving the pivot bolt 108.
[0066] The actuating arm 92 includes: a pivot bar 110; a tooth 112 secured
to the
pivot bar 110 with a flat-head machine screw 114 threaded into a threaded
tooth bore
116 in the pivot bar 110 and with a tooth retainer pin 118 (e.g., a slotted
spring pin) to
prevent rotation of the tooth 112 about the flat-head machine screw 114; a
hollow
cylindrical handle grip 120; a linear spring 122; a linear spring washer 124
and a linear
spring bolt 126.
[0067] The pivot bar 110 includes a bar pivot hole 128 for receiving the
pivot bolt
108. The handle grip 120 includes a linear spring washer seat 130. The pivot
bar 110
includes a threaded linear spring bolt bore 132 for threadedly receiving the
linear spring
bolt 126 to secure the linear spring washer 124 against the linear spring 122,
thus
retaining the linear spring 122 within the linear spring washer seat 130. The
portion of
the pivot bar 110 that in use is within the handle grip 120 has chamfers 134
to reduce
wear.
[0068] The clamp assembly 90 includes a handle grip seat 136 for engaging
the
proximal end of the handle grip 120. When the proximal end of the handle grip
120 is
engaged with the handle grip seat 136, abutting of the proximal end of the
handle grip
120 with the handle grip seat 136 prevents pivotal movement of the actuating
arm 92
from a locked position. In the locked position, the trolley holder 54 may be
in the
engaged position, in which the trolley holder 54 is engaged with a trolley 52
as shown
in Fig. 1 (more specifically, the tooth 112 is engaged with the upper end of
the adjacent
cable-guide end spacer 66).
[0069] The trolley holder 54 is maintained in the locked position (and the
engaged
position), by the linear spring 122, which biases the handle grip 120 towards
engagement with the handle grip seat 136. To change the trolley holder 54 to
the
unlocked and disengaged position (so as to launch the zipline rider), the
operator must
move the handle grip 120 linearly away from engagement with the handle grip
seat 136.
Once the handle grip 120 has been moved linearly sufficiently to clear the
handle grip
seat 136, trolley holder 54 is maintained in engagement with the trolley 52 by
the biasing
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of the actuating arm 92 provided by the pivot spring 100. To disengage the
trolley holder
54 from the trolley 52, the operator must pivot the actuating arm 92 against
the pivot
spring 100 bias so as to disengage the tooth 112 from the upper end of the
adjacent
cable-guide end spacer 68, as shown in Fig. 2.
[0070] Thus, the trolley holder 54 requires two distinct movements by the
operator, linear movement of the handle grip 120 and pivotal movement of the
actuating
arm 92, in order to release a trolley 52, thus reducing the likelihood of
inadvertent early
release.
[0071] In the embodiments shown in the drawings, the trolley holder 54 is
configured such that the conventional trolley 52 abuts (or is very close to)
the clamp
assembly 90, when the conventional trolley 52 is in the position in which the
tooth 112
may be engaged with the upper end of the adjacent cable-guide end spacer 68.
This
configuration is desirable because it prevents potentially damaging contact
between the
adjacent conventional trolley sheave 60, and the pivot bar 110 or tooth 112.
This
configuration is also desirable because when the trolley holder 54 is engaged
with the
trolley 52 , the trolley 52 is essentially held in a fixed position, such that
there is no
discernable distracting "play" or noise associated with intermittent contact
between
components.
[0072] Most various known zipline trolleys include a feature analogous to
the
upper end of the adjacent cable-guide end spacer 68 (i.e., suitable for
engaging a
feature analogous to the tooth 112), but as compared to the upper end of the
adjacent
cable-guide end spacer 68, are different with respect to one or more of: the
distance
from the cable; the position relative to the adjacent end of the trolley
(i.e., the end of the
trolley closest to the trolley holder 54, in use); and the size and shape of
the tooth
receiving cavity. Thus, it is understood that configuring the trolley holder
54 for such
known zipline trolleys would in most instances only require modification of
the pivot bar
110 and/or tooth 112. It is understood that it would be possible to
accommodate many
such known zipline trolleys by having: different interchangeable pivot bar
ends (including
a tooth feature) each configured for a different trolley style; or a different
pivot bar 110
and tooth 112 for each such different trolley style.
14
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CA 02984689 2017-11-01
[0073] To provide a vivid visual indicator of whether the trolley holder 54
is in the
locked or unlocked position, it may be desirable to permanently mark, e.g.,
with bright
paint, that portion of the pivot bar 110 that is visible when the trolley
holder 54 is in the
unlocked and disengaged position but is not visible when the handle grip 120
is engaged
with the handle grip seat 136.
[0074] If the designer considers it desirable, the handle grip seat 136
could be
made longer than indicated in the drawings and other components could be
modified
accordingly, so as to require linear movement of the handle grip 120 to
disengage it from
the handle grip seat 136, greater than suggested by the drawings.
[0075] A possible variation (not show), which may not be desirable due to
increased complexity, involves modifying the end of the pivot bar 110 having
the tooth
112 so as to engage with a trolley 52 moved into contact with the trolley
holder 54 without
requiring the operator to manually move the handle grip 120. For example, the
end of the
pivot bar 110 having the tooth 112 could be separately pivotal, relative to
the end of the
pivot bar 110 supporting the handle grip 120. The end of the pivot bar 110
having the
tooth 112 would be biased (e.g., by a spring) in straight position (i.e.,
essentially as shown
in Fig.1). Responsive to contact between the sloped surfaces of the underside
of the
tooth 112 and the top of an approaching cable-guide end spacer 66, the end of
the pivot
bar 110 having the tooth 112 would initially move up so as to allow the cable-
guide end
spacer 66 to pass the tooth 112 and then, biased by the spring, the tooth 112
would drop
in behind the cable-guide end spacer 66 (e.g., as indicated in Fig. 1).
[0076] Speed limiter embodiments of the present invention and components of
same are shown in Fig. 6 to Fig. 15.
[0077] Fig. 7 shows a small brake disc 140 having three countersunk holes
142.
In the embodiments shown in the drawings, the small brake disc 140 is a 3/32"
thick
copper washer, 3" in diameter, with a 1-1/2" diameter central hole. As shown
in Fig. 8,
in use, two small brake discs 140 are attached to a conventional trolley
sheave 60, one
small brake disc 140 on each side of the conventional trolley sheave 60, with
stainless
steel flat-head bolts (not shown) passing through the countersunk holes 142
into
CA 02984689 2017-11-01
threaded bores (not shown) in the regular hub 80. The small brake discs 140
conventional trolley sheave 60 combination shown in Fig. 8 is at times
referred to herein
as a small brake sheave 144.
[0078] A four-magnet small-brake speed-limiter trolley 146 embodiment is
shown
in Fig. 8. The four-magnet small-brake speed-limiter trolley 146 is configured
for use with
small-brake sheaves 144.
[0079] The four-magnet small-brake speed-limiter trolley 146 includes: four
3/4"
by 1/4" magnets 148 (being cylindrical rare-earth (i.e., neodymium) magnets
having a
diameter of 3/4" and a thickness of 1/4"); four magnet receptacles 150 (being
3/4" holes
in the sides of the four-magnet small-brake speed-limiter trolley 146); and
four single
magnet retainers 152. Each 3/4" by 1/4" magnet 148 is located within a magnet
receptacle 150 and is held in place by magnetic attraction to an associated
overlying
single magnet retainer 152. Each single magnet retainer 152 is made from 1/32"
ferromagnetic sheet metal and is attached to the side of the four-magnet small-
brake-disc
speed-limiter trolley 146 with magnet retainer screws 154.
[0080] In the four-magnet small-brake speed-limiter trolley 146, the magnet
receptacles 150 are positioned so that when used with small-brake sheaves 144,
each
3/4" by 1/4" magnet 148 is proximate the adjacent surface of the small brake
disc 140.
The four-magnet small-brake-disc speed-limiter trolley 146 is configured so
that there is
a 1/32" gap between each 3/4" by 1/4" magnet 148 and the adjacent portion of
the small
brake disc 140. In the four-magnet small-brake speed-limiter trolley 146, the
distance
between the sheave axis of rotation and the center of each magnet receptacle
150 is 1
3/16", such that the radial distance between the sheave axis of rotation and
the side of
each 3/4" by 1/4" magnet 148 furthest from the sheave axis of rotation, is
1/16" less than
the radius of the small brake disc 140. That is, relative to the
circumferential periphery of
the small brake discs 140, each 3/4" by 1/4" magnet 148 is inset 1/16".
[0081] Fig. 10 and Fig. 11 show a large-brake-disc sheave 160 embodiment
having: a large-brake hub 162 (having the same general configuration as the
regular hub
80, but being narrower than the regular hub 80); and two large brake discs
164. In Fig.
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CA 02984689 2017-11-01
10, the large brake disc 164 is represented as transparent such that the large-
brake hub
162 is visible through the large brake disc 164. Each large brake disc 164 has
three
countersunk holes 142. The large brake discs 164 are attached to the large-
brake hub
162, one large brake disc 164 on each side of large-brake hub 162, with
stainless steel
flat-head bolts (not shown) passing through the countersunk holes 142 into
threaded
bores (not shown) in the large-brake hub 162.
[0082] Fig. 12 and 13 show an integral-brake-disc sheave 170 embodiment
having
a brake hub 172, being a single integral component (i.e., a component not
comprising
sub-components fastened one to the other) combining hub and brake disc
features. In
the preferred embodiment, the brake hub 172 comprises a single piece of
aluminum. The
brake hub 172 has an annular channel 174 containing the cable groove 82, and
casting
vent holes 176 for use in casting a suitable cable-groove material (e.g.,
urethane rubber).
[0083] In the embodiments shown in the drawings, the general dimensions of
the
large-brake-disc sheaves 160 are the same as those of the integral-brake-disc
sheaves
170, such that they may be interchangeably installed. In the embodiments shown
in the
drawings, the diameter of the large-brake-disc sheaves 160 and of the integral-
brake-disc
sheaves 170, is 4".
[0084] Fig. 14 and Fig. 15 show a twelve-magnet speed-limiter trolley 180
embodiment and components of same. The twelve-magnet speed-limiter trolley 180
is
configured for use with large-brake-disc sheaves 160 or integral-brake-disc
sheaves 170.
The twelve-magnet speed-limiter trolley 180 includes: twelve (i.e., four sets
of three) 3/4"
by 5/16" magnets 182 (being cylindrical rare-earth (i.e., neodymium) magnets
having a
diameter of 3/4" and a thickness of 5/16"); twelve (i.e., four sets of three)
magnet
receptacles 150, each set of three in the vicinity of a respective axle
support hole 63; and
four triple magnet retainers 184. Each 3/4" by 5/16" magnet 182 is located
within a
magnet receptacle 150 and is held in place by magnetic attraction to an
associated
overlying triple magnet retainer 184. Each triple magnet retainer 184 is made
from 1/32"
ferromagnetic sheet metal and is attached to the side of the twelve-magnet
speed-limiter
trolley 180 with magnet retainer screws 154.
17
CA 02984689 2017-11-01
[0085] In the twelve-magnet speed-limiter trolley 180, the magnet
receptacles 150
are positioned so that when used with the large-brake-disc sheaves 160 or the
integral-
brake-disc sheaves 170, each 3/4" by 5/16" magnet 182 is proximate the
adjacent
surface of the large brake disc 164 or brake hub 172, as the case may be. The
twelve-
magnet speed-limiter trolley 180 is configured so that there is a 1/32" gap
between each
3/4" by 5/16" magnet 182 and the adjacent surface of the large brake disc 164
or brake
hub 172, as the case may be. In the twelve-magnet speed-limiter trolley 180,
the
distance between the sheave axis of rotation and the center of each magnet
receptacle
150 is 1 1/2", such that the radial distance between the sheave axis of
rotation and the
side of each 3/4" by 5/16" magnet 182 furthest from the sheave axis of
rotation, is 1/8"
less than the radius of the the large brake disc 164 and brake hub 172. That
is, relative
to the circumferential periphery of the large brake disc 164 or the brake hub
17, each 3/4"
by 5/16" magnet 182 is inset 1/8".
[0086] The four-magnet small-brake speed-limiter trolley 146 and twelve-
magnet
speed-limiter trolley 180 provide speed limiting by way of eddy current
braking.
[0087] Applicant has run comparison tests of embodiments described herein
and
a trolley without magnets. The tests were run down the same zipline with the
same rider,
done close together, so weather conditions were reasonably consistent between
the test
runs. The tests were performed on a combination of zipline lengths and slopes.
The tests
indicated that as compared to a trolley without magnets: a four-magnet small-
brake
speed-limiter trolley 146 with aluminum conventional trolley sheaves 60
produced an
insignificant speed reduction (no more than about 1%); a four-magnet small-
brake speed-
limiter trolley 146 with small-brake sheaves 144 produced about a 10% speed
reduction;
a twelve-magnet speed-limiter trolley 180 with large-brake-disc sheaves 160
produced
about a 25% speed reduction; and a twelve-magnet speed-limitertrolley 180 with
integral-
brake-disc sheaves 170 produced about a 25% speed reduction.
[0088] The by-product heat generated in the tests was minimal, presumably
in part
due to the relatively high heat conductivity of copper and aluminum.
[0089] Applicant understands that different speed limiting for riders of
different
18
CA 02984689 2017-11-01
weights could be provided by: having different trolleys pre-configured (in
terms of number
and location of magnets) for different weight ranges; configuring the trolleys
to facilitate
operator effected changes to the number of magnets (including altering the
magnet
retainers to enable the operator to readily determine how many magnets are
present in
a particular trolley); etc.
[0090] As well, magnet mounts could be configured so as to adjust the
position of
the magnets relative to the conductor. For example, the gap between the magnet
and
conductor could be adjustable. It is assumed that very small changes in the
gap would
likely have significant effects on the speed-limiting effect and thus that
this sort of
movement (i.e. essentially parallel with the sheave axis of rotation), would
probably only
be of use in turning specific magnets between an "on" position (i.e., in
sufficient proximity
to the conductor to be effective in speed limiting) and an "off' position
(Le., sufficiently
distant from the conductor to be ineffective in speed limiting).
[0091] Alternatively, magnet mounts could be configured to provide operator
controlled movement of the magnets radially relative to the sheave axis of
rotation, so as
to decrease or increase the relative speed at which the conductor passes the
magnet.
[0092] As a further alternative, movement of the magnets could be effected
by
linear actuators or servo motors (or other suitable component) mounted to the
relevant
trolley. With such magnet moving components, speed-limiting effect could be
adjusted
during the zipline ride, for example, responsive to: velocity information
received from a
speed detector (e.g., a speed detector mounted to the trolley, a speed
detection system
including one or more speed detectors (e.g., radar) remote from and in radio
communication with the magnet moving component, etc.); location information
(e.g.,
proximity to the lower end of the cable) for example received from a sensor in
radio
communication with the magnet moving component; combinations of velocity and
location
information; etc.
[0093] As another alternative, the magnetic field source (i.e., one or more
magnets) could be attached to each sheave. With such an arrangement, the
trolley side
plates (generally aluminum) would be the conductor component (and heat
dissipater) of
19
CA 02984689 2017-11-01
the eddy current braking system.
[0094] The scope of the claims should not be limited by the preferred
embodiments
set forth in the examples, but should be given the broadest interpretation
consistent with
the description as a whole.
[0095] The following reference numbers are used herein and in the drawings:
zipline cable 50; conventional trolley 52; trolley holder 54; conventional
trolley sheave 60;
sheave axle pin 62; axle support holes 63; conventional trolley side plate 64;
cable-guide
end spacer 66; middle spacer 68; spreader-bar lanyard connector 70; spreader-
bar
lanyard 72; spreader-bar end 74; spreader bar 76; regular hub 80; cable groove
82;
bearing seat 84; sheave axle pin bearing 86; retainer ring seat 88; clamp
assembly 90;
actuating arm 92; inner block 94; clamp outer housing 96; pivot spring recess
98; pivot
spring 100; clamp hole 102; clamp bolt 104; housing pivot hole 106; pivot bolt
108; pivot
bar 110; tooth 112; flat-head machine screw 114; tooth bore 116; tooth
retainer pin 118;
handle grip 120; linear spring 122; linear spring washer 124; linear spring
bolt 126; bar
pivot hole 128; linear spring washer seat 130; linear spring bolt bore 132;
chamfers 134;
handle grip seat 136; small brake disc 140; countersunk hole 142; small-brake
sheave
144; four-magnet small-brake speed-limiter trolley 146:314" by 1/4" magnet
148; magnet
receptacle 150; single magnet retainer 152; magnet retainer screw 154; large-
brake-disc
sheave 160; large-brake hub 162; large brake disc 164; integral-brake-disc
sheave 170;
brake hub 172; annular channel 174; casting vent hole 176; twelve-magnet speed-
limiter
trolley 180; 3/4" by 5/16" magnet 182; and triple magnet retainer 184.
